In marine seismic surveys it is desired to have accurate information about the depth of the water across the seismic spread. The depth information is important so as to avoid entering bottom reflections in the positioning solutions and to remove waterborne multiples in the seismic processing. Heretofore, water depth is commonly obtained along the seismic survey track by an echo sounder mounted on the hull of the vessel. The depth information obtained in this manner is of little value because it only represents a limited area and does not cover the seismic spread. More accurate depth information for generation of charts may be obtained by making multiple passes with a survey vessel utilizing multiple echo sounders or side scan sonar. This method of obtaining a bathymetric chart of an area is expensive and time consuming.
Therefore, it is a desire to provide a system and method of obtaining water depth information across the seismic survey that addresses drawbacks of the prior art methods. It is a still further desire to provide a method of obtaining water depth information across a seismic spread utilizing an acoustic ranging system in a seismic spread.